Thermally initiated polymerization of olefins using ruthenium or osmium vinylidene complexes

ABSTRACT

The present invention generally relates to the use of certain ruthenium and osmium complexes that are substantially inactive at a first temperature (preferably about room temperature) but becomes progressively more active at a higher second temperature. This difference in reactivities allows the reaction mixture to be formed and manipulated at the first temperature until polymerization is desired. When appropriate, the reaction mixture is heated to a suitable temperature (preferably greater than 50° C.) to activate the catalyst and to initiate polymerization. Because both the initiation and the rate of polymerization may be controlled with temperature, the inventive methods are especially suitable for ring opening metathesis polymerization (“ROMP”) reactions and for molding polymer articles that require extended pot-lives.

This application claims the benefit of U.S. Provisional Application No.60/094,902, filed Jul. 31, 1998 by inventors Robert H. Grubbs and ThomasE. Wilhelm entitled THERMALLY INITIATED POLYMERIZATION OF CYCLIC OLEFINSUSING RUTHENIUM OR OSMIUM VINYLIDENE COMPLEXES. Provisional PatentApplication No. 60/094,902 is incorporated herein by reference.

The U.S. Government has certain rights in this invention pursuant toGrant No. CHE 9509745 awarded by the National Science Foundation.

BACKGROUND

The molding of thermoset polymers is a technologically importantprocessing technique. In one version of this technique, a liquid monomer(e.g., an olefin) and a polymerization catalyst are mixed and poured,cast or injected into a mold. The polymerization proceeds (the article“cures”) and on completion the molded part is removed from the mold forany post cure processing that may be required. The polymerizationreaction mixture may optionally contain additional ingredients such asmodifiers, fillers, reinforcements, and pigments.

The time during which the liquid monomer/catalyst mixture can be workedon after the monomer and catalyst are mixed is called the “pot life” ofthe polymerization reaction mixture. In general, the ability to controlreaction rates increases in importance in the molding of larger parts.To mold successfully, the reaction mixture must not cure so quickly thatthe liquid monomer/catalyst mixture polymerizes before the mixture canbe introduced in to the mold or before the catalyst has had time tocompletely dissolve. However, for convenience and expedient cycle time,it is also important that the catalyst activate within a reasonable timeafter the mold is filled.

Reaction Injection Molding (“RIM”) has previously been used for themolding of polymer articles using a polymerization catalyst and olefinmonomer (U.S. Pat. Nos. 4,400,340 and 4,943,621). In these previousprocesses, a metal (W or Mo) containing compound is dissolved in a firstmonomer stream. The monomer streams are then mixed and the metalcontaining compound and the alkyl aluminum compound react to form anactive catalyst which then catalyzes the polymerization reaction.Because the reaction proceeds extremely quickly once the catalyst isformed, any attempt to modulate the polymerization time relies ondelaying the formation of the active catalyst species. For example, thealkyl aluminum compound stream typically includes an inhibitor, usuallya Lewis base, which suppresses the formation of the catalyst.

As molding processes tackle larger and more complicated polymericcomponents, there is an increasing need for more reliable systems whichcan extend pot life and/or control the rate of metathesis polymerizationreactions.

SUMMARY OF THE INVENTION

The present invention addresses these needs by providing compositionsfor olefin metathesis reaction but whose reaction rate may becontrolled. In general, the catalysts are vinylidene ruthenium andosmium complexes that are substantially inactive at a first temperature(preferably about room temperature) but become progressively more activeat higher temperatures. This difference in reactivities allows thereaction mixture to be formed and manipulated at the first temperatureuntil polymerization is desired. When appropriate, the reaction mixtureis heated to a suitable second temperature (preferably greater thanabout 50° C.) to activate the catalyst to initiate polymerization. Inpreferred embodiments, the heat activation occurs in bursts (as opposedto the continuous application of heat) so as to slow the reaction rateand to allow for a more complete incorporation of the monomers beforecrosslinking. Other than the requirement for heat activation, theinventive compositions may be used in a similar manner as known olefinmetathesis catalysts, particularly ruthenium and osmium complexcatalysts. Because the initiation and rate of polymerization may becontrolled with temperature, the inventive methods are especiallysuitable for ring opening metathesis polymerization (“ROMP”) reactionsand for molding polymer articles that require extended pot-lives.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to methods for extending the pot lifeand/or controlling the rate of metathesis polymerization reaction. Moreparticularly, the present invention relates to the use of a metathesiscatalysts that are substantially inactive at a first temperature butbecome progressively more active at higher temperatures.

In general, the initiation and/or rate of metathesis polymerization iscontrolled by the practice of the inventive methods which comprises:

(i) contacting a metathesis catalyst of the present invention with anolefin in a reaction mixture at a first temperature and

(ii) heating the reaction mixture to a second temperature.

Because the metathesis catalysts of the present invention aresubstantially unreactive at the first temperature (preferably about roomtemperature), the catalyst may be admixed with the reaction mixturecontaining one or more olefin monomers and manipulated at thistemperature until polymerization initiation is desired. At theappropriate time, the mixture containing the catalyst is activated byheating the mixture to a second temperature. In preferred embodiments,the second temperature is at least about 50° C., more preferably atleast about 75° C.

In one embodiment, the metathesis catalysts are of the general formula:

wherein:

M is ruthenium or osmium;

X and X¹ are each independently any anionic ligand;

L and L¹ are each independently any neutral electron donor ligand; and,

R and R¹ are each independently hydrogen or a substituent selected fromthe group consisting of C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl,aryl, C₁-C₂₀ carboxylate, C₁-C₂₀ alkoxy, C₂-C₂₀ alkenyloxy, C₂-C₂₀alkynyloxy, aryloxy, C₂-C₂₀ alkoxycarbonyl, C₁-C₂₀ alkylthio, C₁-C₂₀alkylsulfonyl and C₁-C₂₀ alkylsulfinyl. Optionally, each of the R or R¹substituent group may be substituted with one or more moieties selectedfrom the group consisting of C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, and aryl whichin turn may each be further substituted with one or more groups selectedfrom a halogen, a C₁-C₅ alkyl, C₁-C₅ alkoxy, and phenyl. Moreover, anyof the catalyst ligands may further include one or more functionalgroups. Examples of suitable functional groups include but are notlimited to: alcohol, sulfonic acid, phosphine, thiol, thioether, ketone,aldehyde, ester, ether, amine, imine, amide, imide, imido, nitro,carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide,carboalkoxy, carbamate, acetal, ketal, boronate, cyano, cyanohydrin,hydrazine, oxime, hydrazide, enamine, sulfone, sulfide, sulfenyl, andhalogen.

In preferred embodiments of these catalysts, the R substituent ishydrogen and the R¹ substituent is selected from the group consisting ofC₁-C₁₀ alkyl, C₂-C₁₀ alkenyl, and aryl. In even more preferredembodiments, the R¹ substituent is phenyl, methyl, isopropyl, ortertbutyl, each optionally substituted with one or more moietiesselected from the group consisting of C₁-C₅ alkyl, C₁-C₅ alkoxy, phenyl,and a functional group. In especially preferred embodiments, R¹ isphenyl optionally substituted with one or more moieties selected fromthe group consisting of chloride, bromide, iodide, fluoride, —NO₂,—NMe₂, methyl, methoxy and phenyl.

In preferred embodiments of these catalysts, X and X¹ are eachindependently hydrogen, halide, or one of the following groups: C₁-C₂₀alkyl, aryl, C₁-C₂₀ alkoxide, aryloxide, C₃-C₂₀ alkyldiketonate,aryldiketonate, C₁-C₂₀ carboxylate, arylsulfonate, C₁-C₂₀alkylsulfonate, C₁-C₂₀ alkylthio, C₁-C₂₀ alkylsulfonyl, or C₁-C₂₀alkylsulfinyl. Optionally, X and X¹ may be substituted with one or moremoieties selected from the group consisting of C₁-C₁₀ alkyl, C₁-C₁₀alkoxy, and aryl which in turn may each be further substituted with oneor more groups selected from halogen, C₁-C₅ alkyl, C₁-C₅ alkoxy, andphenyl. In more preferred embodiments, X and X¹ are halide, benzoate,C₁-C₅ carboxylate, C₁-C₅ alkyl, phenoxy, C₁-C₅ alkoxy, C₁-C₅ alkylthio,aryl, and C₁-C₅ alkyl sulfonate. In even more preferred embodiments, Xand X¹ are each halide, CF₃CO₂, CH₃CO₂, CFH₂CO₂, (CH₃)₃CO,(CF₃)₂(CH₃)CO, (CF₃)(CH₃)₂CO, PhO, MeO, EtO, tosylate, mesylate, ortrifluoromethanesulfonate. In the most preferred embodiments, X and X¹are each chloride.

In preferred embodiments of these catalysts, L and L¹ are eachindependently selected from the group consisting of phosphine,sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine,stibine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl,pyridine, thioether and heterocyclic carbene. In more preferredembodiments, L and L¹ are each either (i) a phosphine of the formulaPR³R⁴R⁵, where R³, R⁴, and R⁵ are each independently aryl or C₁-C₁₀alkyl, particularly primary alkyl, secondary alkyl or cycloalkyl or (ii)a heterocyclic carbene of the formula:

wherein R⁶ and R⁷ are each independently selected from the groupconsisting of C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, cycloalkyl,and aryl. R⁶ and R⁷ may each be optionally substituted with one or moresubstituents selected from the group consisting of C₁-C₁₀ alkyl, C₁-C₁₀alkoxy, and aryl which in turn may each be further substituted with oneor more groups selected from halogen, C₁-C₅ alkyl, C₁-C₅ alkoxy, andphenyl. Without being bound by theory, it is believed that bulkier R⁶and R⁷ groups result in catalysts with improved characteristics such asthermal stability. In even more preferred embodiments where L and/or L¹is a heterocyclic carbene, R⁶ and R⁷ are the same and each is of theformula:

wherein:

R⁸ and R⁹ are each independently hydrogen, C₁-C₃ alkyl or C₁-C₃ alkoxy;and,

R¹⁰ is hydrogen, C₁-C₁₀ alkyl, aryl, or a functional group selected fromhydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine,imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate,carbodiimide, carboalkoxy, carbamate, and halogen.

In the most preferred embodiments, L and L¹ are each selected from thegroup consisting of —P(cyclohexyl)₃, —P(cyclopentyl)₃, —P(isopropyl)₃,—P(phenyl)₃, and 1,3-dimesityl imidazole (designated as “IMes”).

In another embodiment, the metathesis catalysts are of the generalformula:

wherein X, X¹, L, and L¹ are as previously described and R⁶, R⁷, and R⁸are the same as R¹.

Examples of the most preferred catalysts for the practice of the presentinvention include:

wherein PCy₃ is selected from the group consisting of —P(cyclohexyl)₃,—P(cyclopentyl)₃, —P(isopropyl)₃, and —P(phenyl)₃.

In preferred embodiments of the inventive method, heat activation occursin bursts rather than through continuous application of heat. Forexample, in the most preferred embodiment, the reaction is placed in aoil bath set at 75° C. for 1 minute every 10 minutes untilpolymerization is completed. It has been unexpectedly found that heatingin a staccato manner versus continuous heating during activation andpolymerization results in a superior polymer due to a more completeincorporation of the monomer before the resulting polymer crosslinks toitself.

Other than the requirement for heat activation, the catalysts of thepresent invention may be used in a similar manner as other olefinmetathesis catalysts. However, the use of these catalysts forring-opening metathesis polymerization (“ROMP”) of functionalized orunfunctionalized cyclic olefins is particularly preferred.

The cyclic olefins may be strained or unstrained, monocyclic orpolycyclic, may optionally include heteroatoms, and may include one ormore functional groups. Suitable cyclic olefins include but are notlimited to norbornene, norbornadiene, dicyclopentadiene, cyclopentene,cycloheptene, cyclooctene, cyclooctadiene, cyclododecene,7-oxanorbornene, 7-oxanorbornadiene, and derivatives therefrom.Illustrative examples of suitable functional groups include but are notlimited to hydroxyl, thiol, ketone, aldehyde, ester, ether, amine,imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate,carbodiimide, carboalkoxy, and halogen. Preferred cyclic olefins includenorbornene and dicyclopentadiene and their respective homologs andderivatives. The use of dicyclopentadiene (“DCPD”) for ROMPpolymerization is particularly preferred.

The ROMP reaction may occur either in the presence or absence of solventand may optionally include formulation auxiliaries. Known auxiliariesinclude antistatics, antioxidants (primary antioxidants, secondaryantioxidants, or mixtures thereof), ceramics, light stabilizers,plasticizers, dyes, pigments, fillers, reinforcing fibers, lubricants,adhesion promoters, viscosity-increasing agents and demolding enhancers.Illustrative examples of fillers for improving the optical physical,mechanical and electrical properties include glass and quartz in theform of powders, beads and fibers, metal and semi-metal oxides,carbonates (i.e. MgCO₃, CaCO₃), dolomite, metal sulfates (such as gypsumand barite), natural and synthetic silicates (i.e. zeolites,wollastonite, feldspars), carbon fibers, and plastic fibers or powders.

Practice of the present invention is particularly suitable for moldingpolymer articles because the pot-life of the reaction is essentiallycontrollable at will. The reaction mixture may either be prepared in themold or prepared outside of the mold and then introduced into the mold.When polymerization is desired, the reaction mixture in the mold isheated to a suitable temperature to initiate polymerization. In contrastto prior art systems that require one or more additives to retard theformation of the active catalyst and/or inhibit monomer polymerization,the present method relies on the inactivity of the catalyst at onetemperature and activity of the catalyst at a second higher temperature.

EXAMPLE 1 Synthesis of (PCy3)2Cl2Ru═Cu═CHPh

In a drybox, 2.5 g of [(p-cymene)RuCl₂]₂ (8.2 mmol Ru) and 4.6 g (16.4mmol) of tricyclohexylphosphine was added into a Fisher-Porter bottle.After connecting the bottle to a Schlenk line, 0.90 mL ofphenylacetylene (8.2 mmol) and 150 mL of dry degassed benzene was added.The reaction mixture was heated to 90° C. for 24 hours, then allowed tocool to room temperature. Upon cooling, a light white-purple solid canbe isolated and washed with pentane, and left to dry in-vacuo, 6.6 g of(PCy₃)₃Cl₂Ru═C═CHPh (hereinafter referred to as a catalyst 1) wasisolated in 97% yield. ¹H NMR: (CD₂Cl₂) 6.82-7.12 (5H, Ru═C═CHPh), 4.35(t, 1H, J=3.7 Hz, Ru═C═CHPh), 1.17-2.24 (˜66H, PCy₃). ³¹P NMR: (CD₂Cl₂):22.42 (s, PCy₃). An osmium counterpart may be synthesized analogously.Other ruthenium/osmium vinylidene derivatives may be prepared usingacetylenes containing the desired substituents.

EXAMPLE 2 Alternate Method for Synthesis of 1

2.5 g of [(p-cymene)RuCl₂](8.2 mmol Ru) and 4.6 g oftricyclohexylphosphine (16.33 mmol) are placed in a Fisher Porter bottleor in a suitably sized thick wall Schlenk flask (with lots ofheadspace). Benzene (60 mL) and phenylacetylene (0.90 mL, 8.2 mmol) arethen added. The headspace is subsequently evacuated, and the reaction isheated at 90° C. for 18 hours. After the reaction mixture is allows tocool, a purple-white solid precipitates, which is filtered and washedwith pentane (3×5 mL). Isolated 6.6 g (97% yield). Alternatively, thisreaction can also be performed with [(benzene)RuCl₂]₂ (0.500 g, 2.0 mmolRu), tricyclohexylphosphine (1.12 g, 4.0 mmol), and phenylacetylene(0.22 mL, 2.0 mmol) as reactants to give 1.59 g (95% yield of 1).

Selected NMR data: (CD₂Cl₂): ¹H: δ 7.10 (dd, Ph—H_(m), J=8.04, 7.32 Hz,2H), 6.88 (d, Ph—H_(o), J=8.04 Hz, 2H), 6.82 (t, Ph—H_(p), J=7.32 Hz,1H), 4.35 (t, Ru═C═CHPh, J=3.7 Hz) 2.61-1.99 (PCy₃, 66H); ³¹P: δ 22.41(s, RuPCy₃).

EXAMPLE 3 (PCy₃)₂Cl₂Ru(═C═CHtBu)(catalyst 2)

In a procedure identical to that immediately above for catalyst 1,benzene (30 mL) and t-butylacetylene (0.269 mL, 3.28 mmol) are added toa mixture of [(p-cymene)RuCl₂]₂ (1 g, 3.28 mmol Ru) andtricyclohexylphosphine (1.84 g, 6.56 mmol). 2.4 g of 2 is isolated for a90% yield.

Selected NMR data: (C₆D₆): ¹H: δ 4.59 (t, Ru═C—CHtBu, J=3.7 Hz); ³¹P: δ18.6 (s, RuPCy₃).

EXAMPLE 4 (PCy₃)₂Cl₂Ru(═C═CHC₄H₉) (catalyst 3)

[(p-cymene)RuCl₂]₂ (0.500 g, 1.63 mmol Ru), tricyclohexylphosphine(0.915 g, 3.27 mmol) are placed in a Fisher Porter bottle or in asuitably sized thick walled Schlenk flask (with lots of headspace).Benzene (30 mL) and 1-hexyne (0.0375 mL, 1.63 mmol) are added, and theheadspace is evacuated. The reaction is stirred at 90° C. for 18 hours,and after cooling only a small amount of solid has precipitated. Thesolvent is removed, and methanol is added to give an orange-pink solid,which is filtered and washed with methanol until the washings arecolorless. 1.2 g of 3 is isolated for a 94% yield.

Selected NMR data: (C₆D₆): ¹H: δ 3.42 (t, Ru═C═CH, J=7.3 Hz), 2.58 (m,RuPCH(CH₂)₅, 6H), 2.35 (q, Ru═C═CH(CH₂)—, J=6.6 Hz, 2H), 2.04, 1.78,1.59, 1.24 (all RuPCH(CH₂)₅, 60H total), 1.63 (br s,Ru═C═CH(CH₂)(CH₂)2(CH₃), J=7.32 Hz, 3H); ³¹P: δ 25.84 (s, RuPCy₃).

EXAMPLE 5 Miscellaneous Notes on the Synthesized Catalysts

All of the above catalysts (when mixed with one or more suitable cyclicolefins) displayed little or no significant polymerization reactionafter 2.5 weeks at room temperature. Each of these catalysts displayedhigher activity at temperatures well above room temperature. Therelative solubility of the catalyst in DCPD were as follows: 1<2<3 (withcatalyst 3 being most soluble in DCPD). In general, catalysts thatdisplay increased solubility in the desired cyclic olefin are preferred.For example, for DCPD polymerization, catalysts that have morehydrophobic substituents (i.e. longer aliphatic substituents) off thevinyl group tend to be more soluble in DCPD and thus are generallypreferred over less hydrophobic catalysts.

EXAMPLE 6 Solventless DCPD Polymerization

10 mg of catalyst 1 was added to 12 mL of stirring DCPD (approximately7500 equivalents of monomer). Not all of the 10 mg of catalyst 1 isimmediately soluble. When this mixture is left at room temperature, thepolymerization reaction rate is negligible even after 24 hours. However,when the mixture is heated to between about 70 and about 80° C.,catalyst 1 completely dissolves and the reaction proceeds to completion.

EXAMPLE 7 DCPD Polymerization in the Presence of Solvent

A 10 mg portion of I is dissolved in a minimum of the solvent CH₂Cl₂ andthen was added to 12 mL of stirring DCPD. As above, polymerization isvirtually undetectable after 24 hours. However, when the mixture isheated to between about 70 and about 80° C., the catalyst is activatedand the reaction proceeds to completion.

EXAMPLE 8 DCPD Polymerization with (PCy₃)(IMes)Cl₂Ru (═C═CHtbu)(catalyst 4)

A mixture of 20 mg (0.024 mmoles) of catalyst 4 was mixed with 15 mL ofDCPD. After 5 minutes at room temperature, no apparent reaction hadtaken place. The side of the reaction vessel was heated with a heat gun.Immediately thereafter, a polymerization front was observed, propagatingfrom the heated site until the entire sample was converted into a solidpart.

EXAMPLE 9 Heat Activation of the Ruthenium/Osmium Vinylidene Complexes

Any suitable method quickly and evenly applying heat to the reactionvessel may be used. For example, the reaction vessel may be placed in anoil bath set to approximately 75° C. and left to stir. In left in theoil bath for about 10-20 minutes, reaction becomes sufficiently viscousso that the reaction stops stirring. A solid material is typicallyobtained after 30 minutes. The resulting material is soft and flexibleand indicates that not all of the DCPD monomer was consumed before thepolymers are crosslinked.

Unexpectedly, better results are obtained when the heat application isin quick bursts and not continuous. For example, when the reactionmixture is placed in a heated oil bath for about 1 minute every 10minutes, a substantially superior product results. In general, the heatburst is applied until the color (i.e. turns an amberish hue in case ofDCPD polymerization) and viscosity (i.e. starts to increase) of themixture indicates that the polymerization has initiated to a suitablelevel. In this manner, because virtually all of the DCPD monomers arereacted before the polymers are crosslinked, the resulting polymerdisplays very desirable strength characteristics. This polymer productappears to be identical in its physical properties as that producedusing a more active carbene catalyst such as (PCy₃)₂Cl₂Ru═CHPh.

Heating with a heat gun for about 1 minute every 10 minutes alsoproduced similar results. The quick bursts of heat appear to lead to amore complete activation of catalyst 1 and a more complete incorporationof the monomer than continuous applications of heat. The time betweenthe burst of heat appears to allow the mixture to cool and sufficientlyslows the polymerization reaction to allow for better mixing of thereactants.

What is claimed is:
 1. A method for controlling the initiation ofmetathesis polymerization comprising: contacting a metathesis catalystwith an olefin in a reaction mixture at a first temperature and heatingthe reaction mixture to a second temperature wherein the metathesiscatalyst is of the formula:

wherein: M is ruthenium or osmium; X and X¹ are each independently anyanionic ligand; L and L¹ are each independently any neutral electrondonor ligand; and, R and R¹ are each independently hydrogen or asubstituent selected from the group consisting of C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, aryl, C₁-C₂₀ carboxylate, C₁-C₂₀ alkoxy, C₂-C₂₀alkenyloxy, C₂-C₂₀ alkynyloxy, aryloxy, C₂-C₂₀ alkoxycarbonyl, C₁-C₂₀alkylthio, C₁-C₂₀ alkylsulfonyl and C₁-C₂₀ alkylsulfinyl, thesubstituent optionally substituted with one or moieties selected fromthe group consisting of C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, and aryl.
 2. Themethod as in claim 1 wherein the first temperature is about roomtemperature.
 3. The method as in claim 2 wherein the second temperatureis at least about 50° C.
 4. The method as in claim 3 wherein thecatalyst includes one or more functional groups selected from the groupconsisting of alcohol, sulfonic acid, phosphine, thiol, thioether,ketone, aldehyde, ester, ether, amine, imine, amide, imide, imido,nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide,carboalkoxy, carbamate, acetal, ketal, boronate, cyano, cyanohydrin,hydrazine, oxime, hydrazide, enamine, sulfone, sulfide, sulfenyl, andhalogen.
 5. The method as in claim 3 wherein: M is ruthenium; R ishydrogen; R¹ is selected from the group consisting of C₁-C₁₀ alkyl,C₂-C₁₀ alkenyl, and aryl; X and X¹ are each independently selected fromthe group consisting of hydrogen, halide, C₁-C₂₀ alkyl, aryl, C₁-C₂₀alkoxide, aryloxide, C₃-C₂₀ alkyldiketonate, aryldiketonate, C₁-C₂₀carboxylate, arylsulfonate, C₁-C₂₀ alkylsul fonate, C₁-C₂₀ alkylthio,C₁-C₂₀ alkylsulfonyl, and C₁-C₂₀ alkylsulfinyl; and L and L¹ are eachindependently selected from the group consisting of phosphine,sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine,stibine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl,pyridine, thioether and heterocyclic carbene.
 6. The method as in claim5 wherein: R¹ is selected from the group consisting of phenyl, methyl,isopropyl, and tertbutyl; X and X¹ are each independently selected fromthe group consisting of halide, CF₃CO₂, CH₃CO₂, CFH₂CO₂, (CH₃)₃CO,(CF₃)₂(CH₃)CO, (CF₃)(CH₃)₂CO, PhO, MeO, EtO, tosylate, mesylate, andtrifluoromethanesulfonate; and L and L¹ are each independently either(i) a phosphine of the formula PR³R⁴R⁵, wherein R³, R⁴, and R⁵ are eachindependently aryl or C₁-C₁₀ alkyl, particularly primary alkyl,secondary alkyl or cycloalkyl or (ii) a heterocyclic carbene of theformula:

wherein R⁶ and R⁷ are each independently selected from the groupconsisting of C₁-C₂₀alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, cycloalkyl,and aryl, each optionally substituted with one or more moieties selectedfrom the group consisting of C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, and aryl. 7.The method as in claim 6 wherein: X and X¹ are each a halide and L andL¹ are selected from a group consisting of —P(cyclohexyl)₃,—P(cyclopentyl)₃, —P(isopropyl)3, —P(phenyl)₃, and IMes wherein IMes is1,3-dimesityl imidazole.
 8. The method as in claim 7 wherein thecatalyst is selected from the group consisting of:

wherein PCy₃ is selected from the group consisting of —P(cyclohexyl)₃,—P(cyclopentyl)₃, —P(isopropyl)₃, and —P(phenyl)₃.
 9. A method forcontrolling the initiation of ROMP polymerization comprising: contactinga metathesis catalyst with a cyclic olefin in a reaction mixture at afirst temperature and heating the reaction mixture to a secondtemperature wherein the metathesis catalyst is of the formula:

wherein: M is ruthenium; R is hydrogen; R¹ is selected from the groupconsisting of C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl, and aryl; X and X¹ are eachindependently selected from the group consisting of halide, CF₃CO₂,CH₃CO₂, CFH₂CO₂, (CH₃)₃CO, (CF₃)₂(CH₃)CO, (CF₃)(CH₃)₂CO, PhO, MeO, EtO,tosylate, mesylate, and trifluoromethanesulfonate; and L and L¹ are eachindependently either (i) a phosphine of the formula PR³R⁴R⁵, wherein R³,R⁴, and R⁵ are each independently aryl or C₁-C₁₀ alkyl, particularlyprimary alkyl, secondary alkyl or cycloalkyl or (ii) a heterocycliccarbene of the formula:

wherein R⁶ and R⁷ are each independently selected from the groupconsisting of C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, cycloalkyl,and aryl, each optionally substituted with one or more moieties selectedfrom the group consisting of C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, and aryl. 10.The method as in claim 9 wherein: R¹ is selected from the groupconsisting of phenyl, methyl, isopropyl, and tertbutyl; X and X¹ areeach chloride; and L and L¹ are each independently selected from a groupconsisting of —P(cyclohexyl)₃, —P(cyclopentyl)₃, —P(isopropyl)₃,—P(phenyl)₃, and IMes wherein IMes is 1,3-dimesityl imidazole.
 11. Themethod as in claim 9 wherein the cyclic olefin is selected from thegroup consisting of norbornene, norbornadiene, dicyclopentadiene,cyclopentene, cycloheptene, cyclooctene, cyclooctadiene, cyclododecene,7-oxanorbornene, 7-oxanorbornadiene, and derivatives therefrom.
 12. Themethod as in claim 9 wherein the first temperature is about roomtemperature.
 13. The method as in claim 9 wherein the second temperatureis at least about 50° C.
 14. The method as in claim 9 wherein the secondtemperature is at least about 75° C.
 15. The method as in claim 11wherein the reaction mixture includes one or more formulationauxiliaries.
 16. The method as in claim 12 wherein the heating occurs inbursts rather than being continuous.
 17. A method of making molded partscomprising: adding a metathesis catalyst and dicyclopentadiene to a moldat a first temperature and heating the mold to a second temperaturewherein the metathesis catalyst is of the formula:

wherein: M is ruthenium; R is hydrogen; R¹ is selected from the groupconsisting of C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl, and aryl; X and X¹ arehalide; and L and L¹ are each independently selected from a groupconsisting of —P(cyclohexyl)₃, —P(cyclopentyl)₃, —P(isopropyl)₃,—P(phenyl)₃, and IMes wherein IMes is 1,3-dimesityl imidazole.
 18. Themethod as in claim 17 wherein the catalyst is selected from the groupconsisting of:

wherein PCy₃ is selected from the group consisting of —P(cyclohexyl)₃,—P(cyclopentyl)₃, —P(isopropyl)₃, and —P(phenyl)₃.
 19. The method as inclaim 17 wherein the first temperature is about room temperature and thesecond temperature is at least about 50° C.
 20. The method as in claim17 wherein the first temperature is about room temperature and thesecond temperature is between about 70° C. and about 80° C.
 21. Themethod as in claim 17 wherein the reaction mixture includes one or moreformulation auxiliaries selected from the group consisting ofantistatics, antioxidants, light stabilizers, plasticizers, dyes,pigments, fillers, reinforcing fibers, lubricants, adhesion promoters,viscosity-increasing agents and demolding enhancers.
 22. The method asin claim 17 wherein the heating occurs in bursts rather than beingcontinuous.
 23. A compound of the formula

wherein: M is ruthenium or osmium; X and X ¹ are each independently anyanionic ligand; R and R ¹ are each independently hydrogen or asubstituent selected from the group consisting of C ₁ -C ₂₀ alkyl, C ₂-C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl, aryl, C ₁ -C ₂₀ carboxylate, C ₁ -C ₂₀alkoxy, C ₂ -C ₂₀ alkenyloxy, C ₂ -C ₂₀ alkynyloxy, aryloxy, C ₂ -C ₂₀alkoxycarbonyl, C ₁ -C ₂₀ alkylthio, C ₁ -C ₂₀ alkylsulfonyl and C ₁ -C₂₀ alkylsulfinyl, the substituent optionally substituted with one ormore moieties selected from the group consisting of C ₁ -C ₁₀ alkyl, C ₁-C ₁₀ alkoxy, and aryl; L is any neutral electron donor ligand; and L ¹a heterocyclic carbene of the formula:

wherein R ⁶ and R ⁷ are each independently selected from the groupconsisting of C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl,cycloalkyl, and aryl, each optionally substituted with one or moremoieties selected from the group consisting of C ₁ -C ₁₀ alkyl, C ₁ -C₁₀ alkoxy, and aryl.
 24. The compound of claim 23, wherein R⁶ and R ⁷are the same and of the formula:

wherein: R ⁸ and R ⁹ are each independently selected from the groupconsisting of hydrogen, C ₁ -C ₃ alkyl and C ₁ -C ₃ alkoxy; and R ¹⁰ isselected from the group consisting of hydrogen, C ₁ -C ₁₀ alkyl, aryl,hydroxyl, thiol, thiioether, ketone, aldehyde, ester, ether, amine,imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate,carbodiimide, carboalkoxy, carbamate, and halogen.
 25. The compound ofclaim 23, wherein X and X¹ are each independently selected from thegroup consisting of hydrogen, halide, C ₁ -C ₂₀ alkyl, aryl, C ₁ -C ₂₀alkoxide, aryloxide, C ₃ -C ₂₀ alkyldiketonate, aryldiketonate, C ₁ -C₂₀ carboxylate, arylsulfonate, C ₁ -C ₂₀ alkylsulfonate, C ₁ -C ₂₀alkylthio, C ₁ -C ₂₀ alkylsulfonyl, and C ₁ -C ₂₀ alkylsulfinyl.
 26. Thecompound of claim 23, wherein X and X¹ are each independently selectedfrom the group consisting of halide, CF ₃ CO ₂ , CH ₃ CO ₂ , CFH ₂ CO ₂,(CH ₃)₃ CO, (CF ₃)₂(CH ₃)CO, (CF ₃)(CH ₃)₂ CO, PhO, MeO, EtO, tosylate,mesylate, and trifluoromethanesulfonate.
 27. The compound of claim 23,wherein X and X¹ are each a halide.
 28. The compound of claim 23,wherein X and X¹ are each chloride.
 29. The compound of claim 23,wherein L is selected from the group consisting of phosphine, sulfonatedphosphine, phosphite, phosphinite, phosphonite, arsine, stibine, ether,amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, thioetherand heterocyclic carbene.
 30. The compound of claim 23, wherein L and L¹are each independently a heterocyclic carbene of the formula:

wherein R ⁶ and R ⁷ are each independently selected from the groupconsisting of C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl,cycloalkyl, and aryl, each optionally substituted with one or moremoieties selected from the group consisting of C ₁ -C ₁₀ alkyl, C ₁ -C₁₀ alkoxy, and aryl.
 31. The compound of claim 30, wherein R⁶ and R ⁷are the same and of the formula:

wherein: R ⁸ and R ⁹ are each independently selected from the groupconsisting of hydrogen, C ₁ -C ₃ alkyl and C ₁ -C ₃ alkoxy; and R ¹⁰ isselected from the group consisting of hydrogen, C ₁ -C ₁₀ alkyl, aryl,hydroxyl, thiol, thiioether, ketone, aldehyde, ester, ether, amine,imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate,carbodiimide, carboalkoxy, carbamate, and halogen.
 32. The compound ofclaim 23 wherein L is selected from the group consisting of—P(cyclohexyl)₃ , —P(cyclopentyl)₃ , —P(isopropyl)₃ , —P(phenyl)₃ , andIMes, wherein IMes is 1,3 dimesityl imidazole.
 33. The compound of claim23 where L and L¹ are both IMes, wherein IMes is 1,3 dimesitylimidazole.
 34. The compound of claim 23, wherein R is hydrogen and R¹ isselected from the group consisting of C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀alkenyl, and aryl.
 35. The compound of claim 23, wherein R is hydrogenand R¹ is selected from the group consisting of phenyl, methyl,isopropyl, and tertbutyl.
 36. A compound of the formula

wherein: M is ruthenium; X and X ¹ are each independently selected fromthe group consisting of halide, CF ₃ CO ₂ , CH ₃ CO ₂ , CFH ₂ CO ₂, (CH₃)₃ CO, (CF ₃)₂(CH ₃)CO, (CF ₃)(CH ₃)₂ CO, PhO, MeO, EtO, tosylate,mesylate, and trifluoromethanesulfonate; R and R ¹ are eachindependently hydrogen or a substituent selected from the groupconsisting of phenyl, methyl, isopropyl, and tertbutyl; and L and L ¹are each independently a heterocyclic carbene of the formula:

wherein R ⁶ and R ⁷ are each independently selected from the groupconsisting of C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl,cycloalkyl, and aryl, each optionally substituted with one or moremoieties selected from the group consisting of C ₁ -C ₁₀ alkyl, C ₁ -C₁₀ alkoxy, and aryl.
 37. A compound of the formula

wherein: M is ruthenium; X and X ¹ are both chloride; R is hydrogen; R ¹is tertbutyl; L is selected from the group consisting of —P(cyclohexyl)₃, —P(cyclopentyl)₃ , —P(isopropyl)₃ , and —P(phenyl)₃ ; and L ¹ is IMes,wherein IMes is 1,3 dimesityl imidazole.